A transflective electrowetting display is disclosed in international patent application WO2006/017129. This known display includes electrowetting elements having a partially, uniform transmissive layer arranged on the second support plate. In a first mode the layer reflects ambient light incident from the viewing side and in a second mode it transmits light incident from the rear side.
Each electrowetting element comprises a transmissive fluid and a black or coloured fluid. The position of the latter fluid in the electrowetting element can be controlled to transmit or absorb light.
A disadvantage of this known transflective display is that the partially transmissive layer requires a special step in the manufacturing process and is therefore relatively expensive to make. Furthermore, the optical performance in the various modes depends on the values of the transmission and reflection coefficient of the layer and their spectral dependence, which will be affected strongly by variations in thickness. As a result, this manufacturing step will be a very yield sensitive step.
Currently it is known that a structured reflector can be provided in the electrowetting elements that are as such subdivided in a transmissive and reflective area, wherein the transmissive area allows for the transmission of light through the electrowetting display and the reflective area allows for reflection of light on the viewing side.
A disadvantage of such electrowetting displays is that the obtainable contrast of the transmissive area is poor with respect to the reflective area, since the optical path length of a light beam passing through the dark fluid of the display in the reflective mode is longer than it is in transmissive mode. Thus the light absorption, and therefore contrast ratio, in reflective mode is better than in transmissive mode. It is therefore an object of the invention to provide a transflective electrowetting display with enhanced contrast in transmissive mode.